diff --git a/compiler/rustc_mir/src/transform/instcombine.rs b/compiler/rustc_mir/src/transform/instcombine.rs index b224df92e9da0..3ed0aea1404d4 100644 --- a/compiler/rustc_mir/src/transform/instcombine.rs +++ b/compiler/rustc_mir/src/transform/instcombine.rs @@ -4,9 +4,14 @@ use crate::transform::{MirPass, MirSource}; use rustc_data_structures::fx::{FxHashMap, FxHashSet}; use rustc_hir::Mutability; use rustc_index::vec::Idx; -use rustc_middle::mir::visit::{MutVisitor, Visitor}; use rustc_middle::mir::{ - BinOp, Body, Constant, Local, Location, Operand, Place, PlaceRef, ProjectionElem, Rvalue, + visit::PlaceContext, + visit::{MutVisitor, Visitor}, + Statement, +}; +use rustc_middle::mir::{ + BinOp, Body, BorrowKind, Constant, Local, Location, Operand, Place, PlaceRef, ProjectionElem, + Rvalue, }; use rustc_middle::ty::{self, TyCtxt}; use std::mem; @@ -71,10 +76,36 @@ impl<'tcx> MutVisitor<'tcx> for InstCombineVisitor<'tcx> { *rvalue = Rvalue::Use(operand); } + if let Some(place) = self.optimizations.unneeded_deref.remove(&location) { + debug!("unneeded_deref: replacing {:?} with {:?}", rvalue, place); + *rvalue = Rvalue::Use(Operand::Copy(place)); + } + self.super_rvalue(rvalue, location) } } +struct MutatingUseVisitor { + has_mutating_use: bool, + local_to_look_for: Local, +} + +impl MutatingUseVisitor { + fn has_mutating_use_in_stmt(local: Local, stmt: &Statement<'tcx>, location: Location) -> bool { + let mut _self = Self { has_mutating_use: false, local_to_look_for: local }; + _self.visit_statement(stmt, location); + _self.has_mutating_use + } +} + +impl<'tcx> Visitor<'tcx> for MutatingUseVisitor { + fn visit_local(&mut self, local: &Local, context: PlaceContext, _: Location) { + if *local == self.local_to_look_for { + self.has_mutating_use |= context.is_mutating_use(); + } + } +} + /// Finds optimization opportunities on the MIR. struct OptimizationFinder<'b, 'tcx> { body: &'b Body<'tcx>, @@ -87,6 +118,85 @@ impl OptimizationFinder<'b, 'tcx> { OptimizationFinder { body, tcx, optimizations: OptimizationList::default() } } + fn find_deref_of_address(&mut self, rvalue: &Rvalue<'tcx>, location: Location) -> Option<()> { + // Look for the sequence + // + // _2 = &_1; + // ... + // _5 = (*_2); + // + // which we can replace the last statement with `_5 = _1;` to avoid the load of `_2`. + if let Rvalue::Use(op) = rvalue { + let local_being_derefed = match op.place()?.as_ref() { + PlaceRef { local, projection: [ProjectionElem::Deref] } => Some(local), + _ => None, + }?; + + let stmt_index = location.statement_index; + // Look behind for statement that assigns the local from a address of operator. + // 6 is chosen as a heuristic determined by seeing the number of times + // the optimization kicked in compiling rust std. + let lower_index = stmt_index.saturating_sub(6); + let statements_to_look_in = self.body.basic_blocks()[location.block].statements + [lower_index..stmt_index] + .iter() + .rev(); + for stmt in statements_to_look_in { + match &stmt.kind { + // Exhaustive match on statements to detect conditions that warrant we bail out of the optimization. + rustc_middle::mir::StatementKind::Assign(box (l, r)) + if l.local == local_being_derefed => + { + match r { + // Looking for immutable reference e.g _local_being_deref = &_1; + Rvalue::Ref( + _, + // Only apply the optimization if it is an immutable borrow. + BorrowKind::Shared, + place_taken_address_of, + ) => { + self.optimizations + .unneeded_deref + .insert(location, *place_taken_address_of); + return Some(()); + } + + // We found an assignment of `local_being_deref` that is not an immutable ref, e.g the following sequence + // _2 = &_1; + // _3 = &5 + // _2 = _3; <-- this means it is no longer valid to replace the last statement with `_5 = _1;` + // _5 = (*_2); + _ => return None, + } + } + + // Inline asm can do anything, so bail out of the optimization. + rustc_middle::mir::StatementKind::LlvmInlineAsm(_) => return None, + + // Check that `local_being_deref` is not being used in a mutating way which can cause misoptimization. + rustc_middle::mir::StatementKind::Assign(box (_, _)) + | rustc_middle::mir::StatementKind::Coverage(_) + | rustc_middle::mir::StatementKind::Nop + | rustc_middle::mir::StatementKind::FakeRead(_, _) + | rustc_middle::mir::StatementKind::StorageLive(_) + | rustc_middle::mir::StatementKind::StorageDead(_) + | rustc_middle::mir::StatementKind::Retag(_, _) + | rustc_middle::mir::StatementKind::AscribeUserType(_, _) + | rustc_middle::mir::StatementKind::SetDiscriminant { .. } => { + if MutatingUseVisitor::has_mutating_use_in_stmt( + local_being_derefed, + stmt, + location, + ) { + return None; + } + } + } + } + } + Some(()) + } + fn find_unneeded_equality_comparison(&mut self, rvalue: &Rvalue<'tcx>, location: Location) { // find Ne(_place, false) or Ne(false, _place) // or Eq(_place, true) or Eq(true, _place) @@ -153,6 +263,8 @@ impl Visitor<'tcx> for OptimizationFinder<'b, 'tcx> { } } + let _ = self.find_deref_of_address(rvalue, location); + self.find_unneeded_equality_comparison(rvalue, location); self.super_rvalue(rvalue, location) @@ -164,4 +276,5 @@ struct OptimizationList<'tcx> { and_stars: FxHashSet, arrays_lengths: FxHashMap>, unneeded_equality_comparison: FxHashMap>, + unneeded_deref: FxHashMap>, } diff --git a/src/test/mir-opt/const_prop/ref_deref.main.ConstProp.diff b/src/test/mir-opt/const_prop/ref_deref.main.ConstProp.diff index 31061233eeecc..e8168c98f0bcd 100644 --- a/src/test/mir-opt/const_prop/ref_deref.main.ConstProp.diff +++ b/src/test/mir-opt/const_prop/ref_deref.main.ConstProp.diff @@ -19,7 +19,7 @@ // + span: $DIR/ref_deref.rs:5:6: 5:10 // + literal: Const { ty: &i32, val: Unevaluated(WithOptConstParam { did: DefId(0:3 ~ ref_deref[317d]::main[0]), const_param_did: None }, [], Some(promoted[0])) } _2 = _4; // scope 0 at $DIR/ref_deref.rs:5:6: 5:10 -- _1 = (*_2); // scope 0 at $DIR/ref_deref.rs:5:5: 5:10 +- _1 = (*_4); // scope 0 at $DIR/ref_deref.rs:5:5: 5:10 + _1 = const 4_i32; // scope 0 at $DIR/ref_deref.rs:5:5: 5:10 StorageDead(_2); // scope 0 at $DIR/ref_deref.rs:5:10: 5:11 StorageDead(_1); // scope 0 at $DIR/ref_deref.rs:5:10: 5:11 diff --git a/src/test/mir-opt/const_prop/ref_deref_project.main.ConstProp.diff b/src/test/mir-opt/const_prop/ref_deref_project.main.ConstProp.diff index e9398df1320ff..fd6388b95e477 100644 --- a/src/test/mir-opt/const_prop/ref_deref_project.main.ConstProp.diff +++ b/src/test/mir-opt/const_prop/ref_deref_project.main.ConstProp.diff @@ -19,7 +19,7 @@ // + span: $DIR/ref_deref_project.rs:5:6: 5:17 // + literal: Const { ty: &(i32, i32), val: Unevaluated(WithOptConstParam { did: DefId(0:3 ~ ref_deref_project[317d]::main[0]), const_param_did: None }, [], Some(promoted[0])) } _2 = &((*_4).1: i32); // scope 0 at $DIR/ref_deref_project.rs:5:6: 5:17 - _1 = (*_2); // scope 0 at $DIR/ref_deref_project.rs:5:5: 5:17 + _1 = ((*_4).1: i32); // scope 0 at $DIR/ref_deref_project.rs:5:5: 5:17 StorageDead(_2); // scope 0 at $DIR/ref_deref_project.rs:5:17: 5:18 StorageDead(_1); // scope 0 at $DIR/ref_deref_project.rs:5:17: 5:18 _0 = const (); // scope 0 at $DIR/ref_deref_project.rs:4:11: 6:2 diff --git a/src/test/mir-opt/inline/inline_closure_borrows_arg.foo.Inline.after.mir b/src/test/mir-opt/inline/inline_closure_borrows_arg.foo.Inline.after.mir index 7475be30c0dff..c49e0218327de 100644 --- a/src/test/mir-opt/inline/inline_closure_borrows_arg.foo.Inline.after.mir +++ b/src/test/mir-opt/inline/inline_closure_borrows_arg.foo.Inline.after.mir @@ -9,13 +9,14 @@ fn foo(_1: T, _2: &i32) -> i32 { let mut _5: (&i32, &i32); // in scope 0 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12 let mut _6: &i32; // in scope 0 at $DIR/inline-closure-borrows-arg.rs:16:7: 16:8 let mut _7: &i32; // in scope 0 at $DIR/inline-closure-borrows-arg.rs:16:10: 16:11 - let mut _8: &i32; // in scope 0 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12 let mut _9: &i32; // in scope 0 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12 + let mut _10: &i32; // in scope 0 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12 scope 1 { debug x => _3; // in scope 1 at $DIR/inline-closure-borrows-arg.rs:12:9: 12:10 scope 2 { - debug r => _8; // in scope 2 at $DIR/inline-closure-borrows-arg.rs:12:14: 12:15 - debug _s => _9; // in scope 2 at $DIR/inline-closure-borrows-arg.rs:12:23: 12:25 + debug r => _9; // in scope 2 at $DIR/inline-closure-borrows-arg.rs:12:14: 12:15 + debug _s => _10; // in scope 2 at $DIR/inline-closure-borrows-arg.rs:12:23: 12:25 + let _8: &i32; // in scope 2 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12 } } scope 3 { @@ -33,13 +34,16 @@ fn foo(_1: T, _2: &i32) -> i32 { _7 = &(*_2); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:10: 16:11 (_5.0: &i32) = move _6; // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12 (_5.1: &i32) = move _7; // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12 - StorageLive(_8); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12 - _8 = move (_5.0: &i32); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12 StorageLive(_9); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12 - _9 = move (_5.1: &i32); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12 - _0 = (*_8); // scope 3 at $DIR/inline-closure-borrows-arg.rs:14:9: 14:18 + _9 = move (_5.0: &i32); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12 + StorageLive(_10); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12 + _10 = move (_5.1: &i32); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12 + StorageLive(_8); // scope 2 at $DIR/inline-closure-borrows-arg.rs:13:13: 13:21 + _8 = _9; // scope 2 at $DIR/inline-closure-borrows-arg.rs:13:24: 13:27 + _0 = (*_9); // scope 3 at $DIR/inline-closure-borrows-arg.rs:14:9: 14:18 + StorageDead(_8); // scope 2 at $DIR/inline-closure-borrows-arg.rs:15:5: 15:6 + StorageDead(_10); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12 StorageDead(_9); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12 - StorageDead(_8); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12 StorageDead(_7); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:11: 16:12 StorageDead(_6); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:11: 16:12 StorageDead(_5); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:11: 16:12 diff --git a/src/test/mir-opt/inst_combine_deref.deep_opt.InstCombine.diff b/src/test/mir-opt/inst_combine_deref.deep_opt.InstCombine.diff new file mode 100644 index 0000000000000..1d20e17a8499b --- /dev/null +++ b/src/test/mir-opt/inst_combine_deref.deep_opt.InstCombine.diff @@ -0,0 +1,92 @@ +- // MIR for `deep_opt` before InstCombine ++ // MIR for `deep_opt` after InstCombine + + fn deep_opt() -> (u64, u64, u64) { + let mut _0: (u64, u64, u64); // return place in scope 0 at $DIR/inst_combine_deref.rs:11:18: 11:33 + let _1: u64; // in scope 0 at $DIR/inst_combine_deref.rs:12:9: 12:11 + let mut _10: u64; // in scope 0 at $DIR/inst_combine_deref.rs:21:6: 21:8 + let mut _11: u64; // in scope 0 at $DIR/inst_combine_deref.rs:21:10: 21:12 + let mut _12: u64; // in scope 0 at $DIR/inst_combine_deref.rs:21:14: 21:16 + scope 1 { + debug x1 => _1; // in scope 1 at $DIR/inst_combine_deref.rs:12:9: 12:11 + let _2: u64; // in scope 1 at $DIR/inst_combine_deref.rs:13:9: 13:11 + scope 2 { + debug x2 => _2; // in scope 2 at $DIR/inst_combine_deref.rs:13:9: 13:11 + let _3: u64; // in scope 2 at $DIR/inst_combine_deref.rs:14:9: 14:11 + scope 3 { + debug x3 => _3; // in scope 3 at $DIR/inst_combine_deref.rs:14:9: 14:11 + let _4: &u64; // in scope 3 at $DIR/inst_combine_deref.rs:15:9: 15:11 + scope 4 { + debug y1 => _4; // in scope 4 at $DIR/inst_combine_deref.rs:15:9: 15:11 + let _5: &u64; // in scope 4 at $DIR/inst_combine_deref.rs:16:9: 16:11 + scope 5 { + debug y2 => _5; // in scope 5 at $DIR/inst_combine_deref.rs:16:9: 16:11 + let _6: &u64; // in scope 5 at $DIR/inst_combine_deref.rs:17:9: 17:11 + scope 6 { + debug y3 => _6; // in scope 6 at $DIR/inst_combine_deref.rs:17:9: 17:11 + let _7: u64; // in scope 6 at $DIR/inst_combine_deref.rs:18:9: 18:11 + scope 7 { + debug z1 => _7; // in scope 7 at $DIR/inst_combine_deref.rs:18:9: 18:11 + let _8: u64; // in scope 7 at $DIR/inst_combine_deref.rs:19:9: 19:11 + scope 8 { + debug z2 => _8; // in scope 8 at $DIR/inst_combine_deref.rs:19:9: 19:11 + let _9: u64; // in scope 8 at $DIR/inst_combine_deref.rs:20:9: 20:11 + scope 9 { + debug z3 => _9; // in scope 9 at $DIR/inst_combine_deref.rs:20:9: 20:11 + } + } + } + } + } + } + } + } + } + + bb0: { + StorageLive(_1); // scope 0 at $DIR/inst_combine_deref.rs:12:9: 12:11 + _1 = const 1_u64; // scope 0 at $DIR/inst_combine_deref.rs:12:14: 12:15 + StorageLive(_2); // scope 1 at $DIR/inst_combine_deref.rs:13:9: 13:11 + _2 = const 2_u64; // scope 1 at $DIR/inst_combine_deref.rs:13:14: 13:15 + StorageLive(_3); // scope 2 at $DIR/inst_combine_deref.rs:14:9: 14:11 + _3 = const 3_u64; // scope 2 at $DIR/inst_combine_deref.rs:14:14: 14:15 + StorageLive(_4); // scope 3 at $DIR/inst_combine_deref.rs:15:9: 15:11 + _4 = &_1; // scope 3 at $DIR/inst_combine_deref.rs:15:14: 15:17 + StorageLive(_5); // scope 4 at $DIR/inst_combine_deref.rs:16:9: 16:11 + _5 = &_2; // scope 4 at $DIR/inst_combine_deref.rs:16:14: 16:17 + StorageLive(_6); // scope 5 at $DIR/inst_combine_deref.rs:17:9: 17:11 + _6 = &_3; // scope 5 at $DIR/inst_combine_deref.rs:17:14: 17:17 + StorageLive(_7); // scope 6 at $DIR/inst_combine_deref.rs:18:9: 18:11 +- _7 = (*_4); // scope 6 at $DIR/inst_combine_deref.rs:18:14: 18:17 ++ _7 = _1; // scope 6 at $DIR/inst_combine_deref.rs:18:14: 18:17 + StorageLive(_8); // scope 7 at $DIR/inst_combine_deref.rs:19:9: 19:11 +- _8 = (*_5); // scope 7 at $DIR/inst_combine_deref.rs:19:14: 19:17 ++ _8 = _2; // scope 7 at $DIR/inst_combine_deref.rs:19:14: 19:17 + StorageLive(_9); // scope 8 at $DIR/inst_combine_deref.rs:20:9: 20:11 +- _9 = (*_6); // scope 8 at $DIR/inst_combine_deref.rs:20:14: 20:17 ++ _9 = _3; // scope 8 at $DIR/inst_combine_deref.rs:20:14: 20:17 + StorageLive(_10); // scope 9 at $DIR/inst_combine_deref.rs:21:6: 21:8 + _10 = _7; // scope 9 at $DIR/inst_combine_deref.rs:21:6: 21:8 + StorageLive(_11); // scope 9 at $DIR/inst_combine_deref.rs:21:10: 21:12 + _11 = _8; // scope 9 at $DIR/inst_combine_deref.rs:21:10: 21:12 + StorageLive(_12); // scope 9 at $DIR/inst_combine_deref.rs:21:14: 21:16 + _12 = _9; // scope 9 at $DIR/inst_combine_deref.rs:21:14: 21:16 + (_0.0: u64) = move _10; // scope 9 at $DIR/inst_combine_deref.rs:21:5: 21:17 + (_0.1: u64) = move _11; // scope 9 at $DIR/inst_combine_deref.rs:21:5: 21:17 + (_0.2: u64) = move _12; // scope 9 at $DIR/inst_combine_deref.rs:21:5: 21:17 + StorageDead(_12); // scope 9 at $DIR/inst_combine_deref.rs:21:16: 21:17 + StorageDead(_11); // scope 9 at $DIR/inst_combine_deref.rs:21:16: 21:17 + StorageDead(_10); // scope 9 at $DIR/inst_combine_deref.rs:21:16: 21:17 + StorageDead(_9); // scope 8 at $DIR/inst_combine_deref.rs:22:1: 22:2 + StorageDead(_8); // scope 7 at $DIR/inst_combine_deref.rs:22:1: 22:2 + StorageDead(_7); // scope 6 at $DIR/inst_combine_deref.rs:22:1: 22:2 + StorageDead(_6); // scope 5 at $DIR/inst_combine_deref.rs:22:1: 22:2 + StorageDead(_5); // scope 4 at $DIR/inst_combine_deref.rs:22:1: 22:2 + StorageDead(_4); // scope 3 at $DIR/inst_combine_deref.rs:22:1: 22:2 + StorageDead(_3); // scope 2 at $DIR/inst_combine_deref.rs:22:1: 22:2 + StorageDead(_2); // scope 1 at $DIR/inst_combine_deref.rs:22:1: 22:2 + StorageDead(_1); // scope 0 at $DIR/inst_combine_deref.rs:22:1: 22:2 + return; // scope 0 at $DIR/inst_combine_deref.rs:22:2: 22:2 + } + } + diff --git a/src/test/mir-opt/inst_combine_deref.do_not_miscompile.InstCombine.diff b/src/test/mir-opt/inst_combine_deref.do_not_miscompile.InstCombine.diff new file mode 100644 index 0000000000000..23c18bde2262b --- /dev/null +++ b/src/test/mir-opt/inst_combine_deref.do_not_miscompile.InstCombine.diff @@ -0,0 +1,85 @@ +- // MIR for `do_not_miscompile` before InstCombine ++ // MIR for `do_not_miscompile` after InstCombine + + fn do_not_miscompile() -> () { + let mut _0: (); // return place in scope 0 at $DIR/inst_combine_deref.rs:54:24: 54:24 + let _1: i32; // in scope 0 at $DIR/inst_combine_deref.rs:55:9: 55:10 + let mut _5: &i32; // in scope 0 at $DIR/inst_combine_deref.rs:59:10: 59:12 + let _6: &i32; // in scope 0 at $DIR/inst_combine_deref.rs:59:10: 59:12 + let _7: (); // in scope 0 at $DIR/inst_combine_deref.rs:60:5: 60:23 + let mut _8: bool; // in scope 0 at $DIR/inst_combine_deref.rs:60:5: 60:23 + let mut _9: bool; // in scope 0 at $DIR/inst_combine_deref.rs:60:13: 60:21 + let mut _10: i32; // in scope 0 at $DIR/inst_combine_deref.rs:60:13: 60:15 + let mut _11: !; // in scope 0 at $SRC_DIR/std/src/macros.rs:LL:COL + scope 1 { + debug x => _1; // in scope 1 at $DIR/inst_combine_deref.rs:55:9: 55:10 + let _2: i32; // in scope 1 at $DIR/inst_combine_deref.rs:56:9: 56:10 + scope 2 { + debug a => _2; // in scope 2 at $DIR/inst_combine_deref.rs:56:9: 56:10 + let mut _3: &i32; // in scope 2 at $DIR/inst_combine_deref.rs:57:9: 57:14 + scope 3 { + debug y => _3; // in scope 3 at $DIR/inst_combine_deref.rs:57:9: 57:14 + let _4: &mut &i32; // in scope 3 at $DIR/inst_combine_deref.rs:58:9: 58:10 + scope 4 { + debug z => _4; // in scope 4 at $DIR/inst_combine_deref.rs:58:9: 58:10 + } + } + } + } + + bb0: { + StorageLive(_1); // scope 0 at $DIR/inst_combine_deref.rs:55:9: 55:10 + _1 = const 42_i32; // scope 0 at $DIR/inst_combine_deref.rs:55:13: 55:15 + StorageLive(_2); // scope 1 at $DIR/inst_combine_deref.rs:56:9: 56:10 + _2 = const 99_i32; // scope 1 at $DIR/inst_combine_deref.rs:56:13: 56:15 + StorageLive(_3); // scope 2 at $DIR/inst_combine_deref.rs:57:9: 57:14 + _3 = &_1; // scope 2 at $DIR/inst_combine_deref.rs:57:17: 57:19 + StorageLive(_4); // scope 3 at $DIR/inst_combine_deref.rs:58:9: 58:10 + _4 = &mut _3; // scope 3 at $DIR/inst_combine_deref.rs:58:13: 58:19 + StorageLive(_5); // scope 4 at $DIR/inst_combine_deref.rs:59:10: 59:12 + StorageLive(_6); // scope 4 at $DIR/inst_combine_deref.rs:59:10: 59:12 + _6 = &_2; // scope 4 at $DIR/inst_combine_deref.rs:59:10: 59:12 +- _5 = &(*_6); // scope 4 at $DIR/inst_combine_deref.rs:59:10: 59:12 ++ _5 = _6; // scope 4 at $DIR/inst_combine_deref.rs:59:10: 59:12 + (*_4) = move _5; // scope 4 at $DIR/inst_combine_deref.rs:59:5: 59:12 + StorageDead(_5); // scope 4 at $DIR/inst_combine_deref.rs:59:11: 59:12 + StorageDead(_6); // scope 4 at $DIR/inst_combine_deref.rs:59:12: 59:13 + StorageLive(_7); // scope 4 at $DIR/inst_combine_deref.rs:60:5: 60:23 + StorageLive(_8); // scope 4 at $DIR/inst_combine_deref.rs:60:5: 60:23 + StorageLive(_9); // scope 4 at $DIR/inst_combine_deref.rs:60:13: 60:21 + StorageLive(_10); // scope 4 at $DIR/inst_combine_deref.rs:60:13: 60:15 + _10 = (*_3); // scope 4 at $DIR/inst_combine_deref.rs:60:13: 60:15 + _9 = Eq(move _10, const 99_i32); // scope 4 at $DIR/inst_combine_deref.rs:60:13: 60:21 + StorageDead(_10); // scope 4 at $DIR/inst_combine_deref.rs:60:20: 60:21 + _8 = Not(move _9); // scope 4 at $DIR/inst_combine_deref.rs:60:5: 60:23 + StorageDead(_9); // scope 4 at $DIR/inst_combine_deref.rs:60:22: 60:23 + switchInt(_8) -> [false: bb1, otherwise: bb2]; // scope 4 at $DIR/inst_combine_deref.rs:60:5: 60:23 + } + + bb1: { + _7 = const (); // scope 4 at $DIR/inst_combine_deref.rs:60:5: 60:23 + StorageDead(_8); // scope 4 at $DIR/inst_combine_deref.rs:60:22: 60:23 + StorageDead(_7); // scope 4 at $DIR/inst_combine_deref.rs:60:22: 60:23 + _0 = const (); // scope 0 at $DIR/inst_combine_deref.rs:54:24: 61:2 + StorageDead(_4); // scope 3 at $DIR/inst_combine_deref.rs:61:1: 61:2 + StorageDead(_3); // scope 2 at $DIR/inst_combine_deref.rs:61:1: 61:2 + StorageDead(_2); // scope 1 at $DIR/inst_combine_deref.rs:61:1: 61:2 + StorageDead(_1); // scope 0 at $DIR/inst_combine_deref.rs:61:1: 61:2 + return; // scope 0 at $DIR/inst_combine_deref.rs:61:2: 61:2 + } + + bb2: { + StorageLive(_11); // scope 4 at $SRC_DIR/std/src/macros.rs:LL:COL + begin_panic::<&str>(const "assertion failed: *y == 99"); // scope 4 at $SRC_DIR/std/src/macros.rs:LL:COL + // mir::Constant + // + span: $SRC_DIR/std/src/macros.rs:LL:COL + // + literal: Const { ty: fn(&str) -> ! {std::rt::begin_panic::<&str>}, val: Value(Scalar()) } + // ty::Const + // + ty: &str + // + val: Value(Slice { data: Allocation { bytes: [97, 115, 115, 101, 114, 116, 105, 111, 110, 32, 102, 97, 105, 108, 101, 100, 58, 32, 42, 121, 32, 61, 61, 32, 57, 57], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [67108863], len: Size { raw: 26 } }, size: Size { raw: 26 }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 26 }) + // mir::Constant + // + span: $DIR/inst_combine_deref.rs:1:1: 1:1 + // + literal: Const { ty: &str, val: Value(Slice { data: Allocation { bytes: [97, 115, 115, 101, 114, 116, 105, 111, 110, 32, 102, 97, 105, 108, 101, 100, 58, 32, 42, 121, 32, 61, 61, 32, 57, 57], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [67108863], len: Size { raw: 26 } }, size: Size { raw: 26 }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 26 }) } + } + } + diff --git a/src/test/mir-opt/inst_combine_deref.dont_opt.InstCombine.diff b/src/test/mir-opt/inst_combine_deref.dont_opt.InstCombine.diff new file mode 100644 index 0000000000000..69036491a10b7 --- /dev/null +++ b/src/test/mir-opt/inst_combine_deref.dont_opt.InstCombine.diff @@ -0,0 +1,53 @@ +- // MIR for `dont_opt` before InstCombine ++ // MIR for `dont_opt` after InstCombine + + fn dont_opt() -> u64 { + let mut _0: u64; // return place in scope 0 at $DIR/inst_combine_deref.rs:43:18: 43:21 + let _1: i32; // in scope 0 at $DIR/inst_combine_deref.rs:44:9: 44:10 + let mut _5: &i32; // in scope 0 at $DIR/inst_combine_deref.rs:48:10: 48:14 + scope 1 { + debug y => _1; // in scope 1 at $DIR/inst_combine_deref.rs:44:9: 44:10 + let _2: &i32; // in scope 1 at $DIR/inst_combine_deref.rs:45:9: 45:13 + scope 2 { + debug _ref => _2; // in scope 2 at $DIR/inst_combine_deref.rs:45:9: 45:13 + let _3: i32; // in scope 2 at $DIR/inst_combine_deref.rs:46:9: 46:10 + scope 3 { + debug x => _3; // in scope 3 at $DIR/inst_combine_deref.rs:46:9: 46:10 + let mut _4: &i32; // in scope 3 at $DIR/inst_combine_deref.rs:47:9: 47:15 + scope 4 { + debug _1 => _4; // in scope 4 at $DIR/inst_combine_deref.rs:47:9: 47:15 + let _6: i32; // in scope 4 at $DIR/inst_combine_deref.rs:49:9: 49:11 + scope 5 { + debug _4 => _6; // in scope 5 at $DIR/inst_combine_deref.rs:49:9: 49:11 + } + } + } + } + } + + bb0: { + StorageLive(_1); // scope 0 at $DIR/inst_combine_deref.rs:44:9: 44:10 + _1 = const 5_i32; // scope 0 at $DIR/inst_combine_deref.rs:44:13: 44:14 + StorageLive(_2); // scope 1 at $DIR/inst_combine_deref.rs:45:9: 45:13 + _2 = &_1; // scope 1 at $DIR/inst_combine_deref.rs:45:16: 45:18 + StorageLive(_3); // scope 2 at $DIR/inst_combine_deref.rs:46:9: 46:10 + _3 = const 5_i32; // scope 2 at $DIR/inst_combine_deref.rs:46:13: 46:14 + StorageLive(_4); // scope 3 at $DIR/inst_combine_deref.rs:47:9: 47:15 + _4 = &_3; // scope 3 at $DIR/inst_combine_deref.rs:47:18: 47:20 + StorageLive(_5); // scope 4 at $DIR/inst_combine_deref.rs:48:10: 48:14 +- _5 = &(*_2); // scope 4 at $DIR/inst_combine_deref.rs:48:10: 48:14 ++ _5 = _2; // scope 4 at $DIR/inst_combine_deref.rs:48:10: 48:14 + _4 = move _5; // scope 4 at $DIR/inst_combine_deref.rs:48:5: 48:14 + StorageDead(_5); // scope 4 at $DIR/inst_combine_deref.rs:48:13: 48:14 + StorageLive(_6); // scope 4 at $DIR/inst_combine_deref.rs:49:9: 49:11 + _6 = (*_4); // scope 4 at $DIR/inst_combine_deref.rs:49:14: 49:17 + _0 = const 0_u64; // scope 5 at $DIR/inst_combine_deref.rs:50:5: 50:6 + StorageDead(_6); // scope 4 at $DIR/inst_combine_deref.rs:51:1: 51:2 + StorageDead(_4); // scope 3 at $DIR/inst_combine_deref.rs:51:1: 51:2 + StorageDead(_3); // scope 2 at $DIR/inst_combine_deref.rs:51:1: 51:2 + StorageDead(_2); // scope 1 at $DIR/inst_combine_deref.rs:51:1: 51:2 + StorageDead(_1); // scope 0 at $DIR/inst_combine_deref.rs:51:1: 51:2 + return; // scope 0 at $DIR/inst_combine_deref.rs:51:2: 51:2 + } + } + diff --git a/src/test/mir-opt/inst_combine_deref.opt_struct.InstCombine.diff b/src/test/mir-opt/inst_combine_deref.opt_struct.InstCombine.diff new file mode 100644 index 0000000000000..c867543d05ea3 --- /dev/null +++ b/src/test/mir-opt/inst_combine_deref.opt_struct.InstCombine.diff @@ -0,0 +1,44 @@ +- // MIR for `opt_struct` before InstCombine ++ // MIR for `opt_struct` after InstCombine + + fn opt_struct(_1: S) -> u64 { + debug s => _1; // in scope 0 at $DIR/inst_combine_deref.rs:30:15: 30:16 + let mut _0: u64; // return place in scope 0 at $DIR/inst_combine_deref.rs:30:24: 30:27 + let _2: &u64; // in scope 0 at $DIR/inst_combine_deref.rs:31:9: 31:10 + let mut _5: u64; // in scope 0 at $DIR/inst_combine_deref.rs:34:5: 34:7 + let mut _6: u64; // in scope 0 at $DIR/inst_combine_deref.rs:34:10: 34:11 + scope 1 { + debug a => _2; // in scope 1 at $DIR/inst_combine_deref.rs:31:9: 31:10 + let _3: &u64; // in scope 1 at $DIR/inst_combine_deref.rs:32:9: 32:10 + scope 2 { + debug b => _3; // in scope 2 at $DIR/inst_combine_deref.rs:32:9: 32:10 + let _4: u64; // in scope 2 at $DIR/inst_combine_deref.rs:33:9: 33:10 + scope 3 { + debug x => _4; // in scope 3 at $DIR/inst_combine_deref.rs:33:9: 33:10 + } + } + } + + bb0: { + StorageLive(_2); // scope 0 at $DIR/inst_combine_deref.rs:31:9: 31:10 + _2 = &(_1.0: u64); // scope 0 at $DIR/inst_combine_deref.rs:31:13: 31:17 + StorageLive(_3); // scope 1 at $DIR/inst_combine_deref.rs:32:9: 32:10 + _3 = &(_1.1: u64); // scope 1 at $DIR/inst_combine_deref.rs:32:13: 32:17 + StorageLive(_4); // scope 2 at $DIR/inst_combine_deref.rs:33:9: 33:10 +- _4 = (*_2); // scope 2 at $DIR/inst_combine_deref.rs:33:13: 33:15 ++ _4 = (_1.0: u64); // scope 2 at $DIR/inst_combine_deref.rs:33:13: 33:15 + StorageLive(_5); // scope 3 at $DIR/inst_combine_deref.rs:34:5: 34:7 +- _5 = (*_3); // scope 3 at $DIR/inst_combine_deref.rs:34:5: 34:7 ++ _5 = (_1.1: u64); // scope 3 at $DIR/inst_combine_deref.rs:34:5: 34:7 + StorageLive(_6); // scope 3 at $DIR/inst_combine_deref.rs:34:10: 34:11 + _6 = _4; // scope 3 at $DIR/inst_combine_deref.rs:34:10: 34:11 + _0 = Add(move _5, move _6); // scope 3 at $DIR/inst_combine_deref.rs:34:5: 34:11 + StorageDead(_6); // scope 3 at $DIR/inst_combine_deref.rs:34:10: 34:11 + StorageDead(_5); // scope 3 at $DIR/inst_combine_deref.rs:34:10: 34:11 + StorageDead(_4); // scope 2 at $DIR/inst_combine_deref.rs:35:1: 35:2 + StorageDead(_3); // scope 1 at $DIR/inst_combine_deref.rs:35:1: 35:2 + StorageDead(_2); // scope 0 at $DIR/inst_combine_deref.rs:35:1: 35:2 + return; // scope 0 at $DIR/inst_combine_deref.rs:35:2: 35:2 + } + } + diff --git a/src/test/mir-opt/inst_combine_deref.rs b/src/test/mir-opt/inst_combine_deref.rs new file mode 100644 index 0000000000000..3be8c2f3ac732 --- /dev/null +++ b/src/test/mir-opt/inst_combine_deref.rs @@ -0,0 +1,69 @@ +// compile-flags: -O +// EMIT_MIR inst_combine_deref.simple_opt.InstCombine.diff +fn simple_opt() -> u64 { + let x = 5; + let y = &x; + let z = *y; + z +} + +// EMIT_MIR inst_combine_deref.deep_opt.InstCombine.diff +fn deep_opt() -> (u64, u64, u64) { + let x1 = 1; + let x2 = 2; + let x3 = 3; + let y1 = &x1; + let y2 = &x2; + let y3 = &x3; + let z1 = *y1; + let z2 = *y2; + let z3 = *y3; + (z1, z2, z3) +} + +struct S { + a: u64, + b: u64, +} + +// EMIT_MIR inst_combine_deref.opt_struct.InstCombine.diff +fn opt_struct(s: S) -> u64 { + let a = &s.a; + let b = &s.b; + let x = *a; + *b + x +} + +// EMIT_MIR inst_combine_deref.dont_opt.InstCombine.diff +// do not optimize a sequence looking like this: +// _1 = &_2; +// _1 = _3; +// _4 = *_1; +// as the _1 = _3 assignment makes it not legal to replace the last statement with _4 = _2 +fn dont_opt() -> u64 { + let y = 5; + let _ref = &y; + let x = 5; + let mut _1 = &x; + _1 = _ref; + let _4 = *_1; + 0 +} + +// EMIT_MIR inst_combine_deref.do_not_miscompile.InstCombine.diff +fn do_not_miscompile() { + let x = 42; + let a = 99; + let mut y = &x; + let z = &mut y; + *z = &a; + assert!(*y == 99); +} + +fn main() { + simple_opt(); + deep_opt(); + opt_struct(S { a: 0, b: 1 }); + dont_opt(); + do_not_miscompile(); +} diff --git a/src/test/mir-opt/inst_combine_deref.simple_opt.InstCombine.diff b/src/test/mir-opt/inst_combine_deref.simple_opt.InstCombine.diff new file mode 100644 index 0000000000000..f52dfe379ca30 --- /dev/null +++ b/src/test/mir-opt/inst_combine_deref.simple_opt.InstCombine.diff @@ -0,0 +1,34 @@ +- // MIR for `simple_opt` before InstCombine ++ // MIR for `simple_opt` after InstCombine + + fn simple_opt() -> u64 { + let mut _0: u64; // return place in scope 0 at $DIR/inst_combine_deref.rs:3:20: 3:23 + let _1: u64; // in scope 0 at $DIR/inst_combine_deref.rs:4:9: 4:10 + scope 1 { + debug x => _1; // in scope 1 at $DIR/inst_combine_deref.rs:4:9: 4:10 + let _2: &u64; // in scope 1 at $DIR/inst_combine_deref.rs:5:9: 5:10 + scope 2 { + debug y => _2; // in scope 2 at $DIR/inst_combine_deref.rs:5:9: 5:10 + let _3: u64; // in scope 2 at $DIR/inst_combine_deref.rs:6:9: 6:10 + scope 3 { + debug z => _3; // in scope 3 at $DIR/inst_combine_deref.rs:6:9: 6:10 + } + } + } + + bb0: { + StorageLive(_1); // scope 0 at $DIR/inst_combine_deref.rs:4:9: 4:10 + _1 = const 5_u64; // scope 0 at $DIR/inst_combine_deref.rs:4:13: 4:14 + StorageLive(_2); // scope 1 at $DIR/inst_combine_deref.rs:5:9: 5:10 + _2 = &_1; // scope 1 at $DIR/inst_combine_deref.rs:5:13: 5:15 + StorageLive(_3); // scope 2 at $DIR/inst_combine_deref.rs:6:9: 6:10 +- _3 = (*_2); // scope 2 at $DIR/inst_combine_deref.rs:6:13: 6:15 ++ _3 = _1; // scope 2 at $DIR/inst_combine_deref.rs:6:13: 6:15 + _0 = _3; // scope 3 at $DIR/inst_combine_deref.rs:7:5: 7:6 + StorageDead(_3); // scope 2 at $DIR/inst_combine_deref.rs:8:1: 8:2 + StorageDead(_2); // scope 1 at $DIR/inst_combine_deref.rs:8:1: 8:2 + StorageDead(_1); // scope 0 at $DIR/inst_combine_deref.rs:8:1: 8:2 + return; // scope 0 at $DIR/inst_combine_deref.rs:8:2: 8:2 + } + } +